Thumper Posted February 24, 2006 Share Posted February 24, 2006 I have been having an oil problem on/off for awhile. Whenever I install a new or junkyard oil pump the oil pressure is fine for about a day or two. Then after that it start to goe low. Like 15psi at 3000rpms low. But for the first day or two its up at 30psi+. The drop is not gradual it might go down 5psi or so at first but then one minute its fine and then 10minutes later its low. I have installed 4 oil pumps now and all of them have done this. I have also replaced the oil pressure springs with competition ones from courtesy, and i've replaced the oil pump shaft with no changes. When I remove the old oil pump the oil pump shaft is hard to turn and remove from the oil pump housing. But when I install a new/junkyard oil pump it slides on and off easily and turns easily. So between the two days of installing it and when I notice the pressure is low my oil presssure falls off and the clearances between the shaft and oil pump housing get smaller. I know it can't be the shaft slipping because the distributor is on the same shaft and the car runs great. Very little if any oil comes out tailpipe in the morning. And compression on the engine is ok. I do have a oil leak around the lower portion of the front cover maybe from the oil pump gasket. I have always used a factory gasket on the oil pump. I do not have a gasket on the distributor. BTW all pressure readings are done with an autometer mechanical pressure gauge. I have checked the gauge with another known good one and both read the same. Any input is greatly appreciated thanks. Quote Link to comment Share on other sites More sharing options...
JMortensen Posted February 24, 2006 Share Posted February 24, 2006 Sounds like you haven't pulled the pumps apart. I'd be curious to find out if the gears or the case of the pump are really badly scored or anything like that. Pretty bizarre problem, as L6 pumps are usually very reliable. I'd consider replacing the oil pump drive again, but this time replace it and the gear on the crank together. You say the distributor works fine, but its at the end of a very long shaft which goes through the timing cover as well, so I think it might be somewhat isolated from vibration or out of round problems that could be screwing up the pumps. Kind of a SWAG, but that's pretty much all I've got... Other than that the thing that usually ruins the pumps is metal in the engine. I kinda doubt that you could have enough metal in there to trash 4 pumps but not to screw up anything else, which makes me think that the shaft or the crank gear are misaligned, causing the pump to grind itself to pieces. Quote Link to comment Share on other sites More sharing options...
Thumper Posted February 24, 2006 Author Share Posted February 24, 2006 Ok I took apart two oil pumps. One known good one and the one that has been in the engine for maybe 5hrs of driving time. The bad one has scratches and gouges on all metal clearance parts is very hard to turn by hand. The oil pump shaft cog is in good condition and is installed the correct way. No rounded edges or scratches. I can not think of what is causing this. Both of the bad parts are on the right. Thanks Quote Link to comment Share on other sites More sharing options...
Silent Posted February 24, 2006 Share Posted February 24, 2006 flush the oil system. looks like there is some metal floating around in there Quote Link to comment Share on other sites More sharing options...
Thumper Posted February 24, 2006 Author Share Posted February 24, 2006 I was thinking the same thing. But i've changed my oil atleast twice since then. I'm about to do it again just to be sure though. Quote Link to comment Share on other sites More sharing options...
Synlubes Posted February 24, 2006 Share Posted February 24, 2006 Is this a fresh rebuild or a old engine? Old engine, maybe worn bearings with to much clearance??? This may not solve this issue but would help in testing when the oil pressure drops. Find a second valve cover and cut the top center out about 3" wide and full length. Get a small piece of plexiglass to cover the gap cut in the v/c. Use some sealant/adhesive and cover the top of the valve cover with it. Put it on the car and you will be able to see the oiling taking place on the top side of the engine. I had a problem with dropping oil pressure after the engine came up it temp. Mine ended up bearing main bearing clearance was to tight. Very small particles of bearing material wiped out a comp cam and rockers and oil pump. Again, just some ideas. Quote Link to comment Share on other sites More sharing options...
proxlamus© Posted February 24, 2006 Share Posted February 24, 2006 what kinda oil are you using? Like a 20w50? 10w30?? how cold is it outside? Im very confused how you have this issue... but with thicker oil, you should run some more pressure... by a little bit Quote Link to comment Share on other sites More sharing options...
Thumper Posted February 25, 2006 Author Share Posted February 25, 2006 Is this a fresh rebuild or a old engine?Old engine' date=' maybe worn bearings with to much clearance??? [/quote'] Junkyard motor but the oil problem is constant. With the car cold it doesnt go up as much as it use too. And just slightly warm the pressure is way lower than it usually is hot. So I don't think its just temperature. I am running synthetic 10w30 mobil 1. Its 50 degrees out. And I don't think thicker oil will help that much because I have found scaring on the oil pump itself. Quote Link to comment Share on other sites More sharing options...
TheNeedForZ Posted February 25, 2006 Share Posted February 25, 2006 Could it be the pickup? There is a gasket between the pickup tube and the bottom of the block, maybe the pickup tube bolts wiggled loose and air got into the oil line. Quote Link to comment Share on other sites More sharing options...
Guest 73Turbo240z Posted February 25, 2006 Share Posted February 25, 2006 gotta teach your sister how to shoot macro modes w/ out a flash ted. Quote Link to comment Share on other sites More sharing options...
Cody 82 ZXT Posted February 25, 2006 Share Posted February 25, 2006 The look of that pump says to me that there is alot of trash in that motor. Pull your oil filter off and cut it open with a pipe cutter that does not make shavings. Pull the filter media out and take a look inside it. I've pulled pumps out of 170,000 mile motors that did not look that bad. May be time for a rebuild. Is this a new J/Y motor or one that you've been running for awhile? Quote Link to comment Share on other sites More sharing options...
Thumper Posted February 25, 2006 Author Share Posted February 25, 2006 Its been running for awhile. It has 4 piston skirts broken off the pistons. I dropped the oil pan and cleaned it out and took a look at everything else about 6 months ago. On some of the parts its look like the two parts of the oil pump were rubbing against each other, and not metal flakes scrapeing. They have matching scratch marks. I think I might drop the oil pan again and check if there are alot of shavings down there and while i'm there i'll check the pickup tube. Also I will do an engine flush see what that does. If it eats another oil pump I might pull the engine and tear it down. Quote Link to comment Share on other sites More sharing options...
Cody 82 ZXT Posted February 26, 2006 Share Posted February 26, 2006 Not saying this is what's happening but, it may have finally have come time for the 4 pistons skirts to have become an issue. I think your on the right track with pulling the pan to see what's in the bottom of it. I personally would stay away from the motor flush unless your going to just pour it in and let it soak the bottom of the pan and then drain it. That stuff really turns your oil into water. If your wanting to flush the motor I think I would buy to or three rounds of really cheap oil changes and run those thru it after 100 to 300 miles each. Quote Link to comment Share on other sites More sharing options...
Guest 73Turbo240z Posted February 26, 2006 Share Posted February 26, 2006 what about the old trick of adding 1 quart of ATF in place of 1 quart of oil... i'd heard the additional detergents are good for giving the block a good scrub down... run that for about 20 miles or so then change? Quote Link to comment Share on other sites More sharing options...
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